Method of manufacturing thin-film magnetic head

ABSTRACT

In a method of manufacturing a thin-film magnetic head, a bottom pole layer is formed and a thin-film coil is formed on the bottom pole layer. A recording gap layer is then formed on the pole portion of the bottom pole layer. Next, the recording gap layer and a portion of the bottom pole layer are selectively etched through the use of a mask so as to form an end portion of the recording gap layer for defining the throat height. Next, a nonmagnetic layer is formed to fill the etched portions of the recording gap layer and the bottom pole layer while the mask is left unremoved. Next, the mask is removed, and the top surfaces of the recording gap layer and the nonmagnetic layer are flattened by polishing. A top pole layer is formed on the flattened top surfaces of the recording gap layer and the nonmagnetic layer.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of manufacturing a thin-filmmagnetic head having at least an induction-type electromagnetictransducer.

2. Description of the Related Art

Recent years have seen significant improvements in the areal recordingdensity of hard disk drives. In particular, areal recording densities oflatest hard disk drives have reached 80 to 100 gigabytes per platter andare even exceeding that level. It is required to improve the performanceof thin-film magnetic heads, accordingly.

Among the thin-film magnetic heads, widely used are composite thin-filmmagnetic heads made of a layered structure including a recording (write)head having an induction-type electromagnetic transducer for writing anda reproducing (read) head having a magnetoresistive element (that may behereinafter called an MR element) for reading.

In general, the write head incorporates: a medium facing surface (an airbearing surface) that faces toward a recording medium; a bottom polelayer and a top pole layer that are magnetically coupled to each otherand include magnetic pole portions opposed to each other and located inregions of the pole layers on a side of the medium facing surface; arecording gap layer provided between the magnetic pole portions of thetop and bottom pole layers; and a thin-film coil at least part of whichis disposed between the top and bottom pole layers and insulated fromthe top and bottom pole layers.

Higher track densities on a recording medium are essential to enhancingthe recording density among the performances of the write head. Toachieve this, it is required to implement the write head of a narrowtrack structure in which the track width, that is, the width of the twomagnetic pole portions opposed to each other with the recording gaplayer disposed in between, the width being taken in the medium facingsurface, is reduced down to microns or the order of submicron.Semiconductor process techniques are utilized to achieve the write headhaving such a structure. In addition, many write heads have a trimstructure to prevent an increase in the effective track width due toexpansion of a magnetic flux generated in the pole portions in themedium facing surface. The trim structure is a configuration in whichthe pole portion of the top pole layer, the recording gap layer and aportion of the bottom pole layer have the same width taken in the mediumfacing surface. This structure is formed by etching the recording gaplayer and the portion of the bottom pole layer, using the pole portionof the top pole layer as a mask.

One of the parameters that affect the writing characteristics of thethin-film magnetic head is the throat height. The throat height is thelength (height) of the pole portions, that is, the portions of the twopole layers opposed to each other with the recording gap layer inbetween, as taken from the medium-facing-surface-side end to the otherend. The throat height affects the intensity and distribution of themagnetic field generated near the recording gap layer in the mediumfacing surface. Therefore, it is required to control the throat heightwith accuracy to control the writing characteristics of the thin-filmmagnetic head with accuracy.

The throat height may be determined by forming a stepped portion in thebottom or top pole layer. If the throat height is determined by forminga stepped portion in the bottom pole layer, it is possible to form thetop pole layer defining the track width on a flat surface and to formthe pole portion of the top pole layer that is small in size withaccuracy. Methods of determining the throat height by forming a steppedportion in the bottom pole layer are disclosed in, for example, the U.S.Pat. No. 6,259,583B1, the U.S. Pat. No. 6,400,525B1, and the U.S. Pat.No. 5,793,578.

Reference is now made to FIG. 21 and FIG. 22 to describe a typicalmethod of forming the stepped portion for defining the throat height inthe bottom pole layer. In this method, as shown in FIG. 21, an etchingmask 102 is formed on a bottom pole layer 101, and the bottom pole layer101 is selectively etched through the use of the mask 102 to form agroove 103 in the bottom pole layer 101. According to this method, it isdifficult to form sidewalls 104 making up the groove 103 formed in thebottom pole layer 101 in such a manner that the sidewalls 104 areorthogonal to the top surface of the bottom pole layer 101. Inparticular, the surfaces of portions 104 a of the sidewalls 104 close tothe top surface of the bottom pole layer 101 form a greater angle withrespect to the direction orthogonal to the top surface of the bottompole layer 101.

A recording gap layer is formed on the bottom pole layer 101 that hasbeen etched. In general, before the recording gap layer is formed, asshown in FIG. 22, the mask 102 is removed and then an insulating layer106 is formed to cover the bottom pole layer 101. The insulating layer106 is polished so that the bottom pole layer 101 is exposed to flattenthe top surfaces of the bottom pole layer 101 and the insulating layer106. The recording gap layer is formed on these flattened surfaces. InFIG. 22 numeral 107 indicates the level in which polishing is stopped.

According to such a conventional method, the surfaces of the portions104 a of the sidewalls 104 of the groove 103 close to the top surface ofthe bottom pole layer 101 form a greater angle with respect to thedirection orthogonal to the top surface of the bottom pole layer 101, asdescribed above. As a result, the method has a problem that the throatheight greatly varies depending on the level in which polishing isstopped.

OBJECT AND SUMMARY OF THE INVENTION

It is an object of the invention to provide a method of manufacturing athin-film magnetic head to form the pole portion for defining the trackwidth that is small in size with precision and to control the throatheight with accuracy.

A thin-film magnetic head fabricated through a method of manufacturingthe thin-film magnetic head of the invention comprises: a medium facingsurface that faces toward a recording medium; a first pole layer and asecond pole layer that are magnetically coupled to each other andinclude magnetic pole portions opposed to each other and located inregions of the pole layers on a side of the medium facing surface; a gaplayer provided between the pole portion of the first pole layer and thepole portion of the second pole layer; and a thin-film coil, at leastpart of the coil being disposed between the first and second pole layersand insulated from the first and second pole layers. The second polelayer incorporates a track width defining portion for defining the trackwidth.

The method of manufacturing the thin-film magnetic head of the inventioncomprises the steps of forming the first pole layer; forming thethin-film coil on the first pole layer; forming the gap layer on thepole portion of the first pole layer; forming a mask on the gap layerfor making an end portion of the gap layer for defining a throat height;forming the end portion of the gap layer by selectively etching the gaplayer and a portion of the first pole layer through the use of the mask;forming a nonmagnetic layer so as to fill etched portions of the gaplayer and the first pole layer while the mask is left unremoved;removing the mask after the nonmagnetic layer is formed; and forming thesecond pole layer on the gap layer after the mask is removed.

According to the method of the invention, the gap layer and the portionof the first pole layer are selectively etched through the use of themask, so that the end portion of the gap layer for defining the throatheight is formed. The nonmagnetic layer is then formed to fill theetched portions of the gap layer and the first pole layer while the maskis left unremoved. The mask is then removed and the second pole layer isformed on the gap layer. It is thereby possible to form the pole portionfor defining the track width that is small-sized with precision and tocontrol the throat height with accuracy.

According to the method of the invention, the throat height may bedefined by the position in which the end portion of the gap layer andthe first pole layer are in contact with each other. In this case, themethod may further comprise the step of flattening the top surfaces ofthe gap layer and the nonmagnetic layer by polishing, the step beingprovided between the step of removing the mask and the step of formingthe second pole layer. The depth to which the polishing is performed inthe step of flattening may fall within a range of approximately 10 to 50nm inclusive. The track width defining portion of the second pole layermay be made flat.

According to the method of the invention, in the step of forming thenonmagnetic layer, at least a portion of the nonmagnetic layer near theend portion of the gap layer may be disposed to protrude upward andreach a level higher than the top surface of the gap layer, and thethroat height may be defined by the position in which the end portion ofthe gap layer and the second pole layer are in contact with each other.In this case, the second pole layer may incorporate a first magneticlayer disposed on the gap layer and a second magnetic layer disposed onthe first magnetic layer. In addition, the step of forming the secondpole layer may include the steps of forming the first magnetic layer onthe gap layer; flattening a top surface of the first magnetic layer bypolishing; and forming the second magnetic layer on the flattened topsurface of the first magnetic layer. The depth to which the polishing isperformed in the step of flattening may fall within a range ofapproximately 10 to 50 nm inclusive.

The method of the invention may further comprise the step of etching thegap layer and a portion of the first pole layer to align with a width ofthe track width defining portion of the second pole layer, so that eachof the portion of the first pole layer, the gap layer and the trackwidth defining portion has a width taken in the medium facing surfacethat is equal to the track width.

In the method of the invention the step of forming the second pole layermay include the steps of forming a magnetic layer on the gap layer; andetching the magnetic layer by reactive ion etching so that the magneticlayer etched serves as the second pole layer, wherein the gap layer ismade of a nonmagnetic inorganic material. In this case, the nonmagneticinorganic material may be one of the group consisting of alumina,silicon carbide and aluminum nitride.

According to the method of the invention, the gap layer and the portionof the first pole layer are selectively etched through the use of themask, so that the end portion of the gap layer for defining the throatheight is formed. The nonmagnetic layer is then formed to fill theetched portions of the gap layer and the first pole layer while the maskis left unremoved. The mask is then removed and the second pole layer isformed on the gap layer. It is thereby possible to form the second polelayer including the track width defining portion on a flat or nearlyflat surface. According to the invention, the throat height is definedby the level of the end portion of the gap layer for defining the throatheight, and there is no variation in throat height due to polishing ofthe first pole layer. As thus described, according to the invention, itis possible to form the pole portion for defining the track width thatis small-sized with precision and to control the throat height withaccuracy.

Other and further objects, features and advantages of the invention willappear more fully from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A and FIG. 1B are cross-sectional views for illustrating a step ina method of manufacturing a thin-film magnetic head of a firstembodiment of the invention.

FIG. 2A and FIG. 2B are cross-sectional views for illustrating a stepthat follows FIG. 1A and FIG. 1B.

FIG. 3A and FIG. 3B are cross-sectional views for illustrating a stepthat follows FIG. 2A and FIG. 2B.

FIG. 4A and FIG. 4B are cross-sectional views for illustrating a stepthat follows FIG. 3A and FIG. 3B.

FIG. 5A and FIG. 5B are cross-sectional views for illustrating a stepthat follows FIG. 4A and FIG. 4B.

FIG. 6A and FIG. 6B are cross-sectional views for illustrating a stepthat follows FIG. 5A and FIG. 5B.

FIG. 7A and FIG. 7B are cross-sectional views for illustrating a stepthat follows FIG. 6A and FIG. 6B.

FIG. 8A and FIG. 8B are cross-sectional views for illustrating a stepthat follows FIG. 7A and FIG. 7B.

FIG. 9A and FIG. 9B are cross-sectional views for illustrating a stepthat follows FIG. 8A and FIG. 8B.

FIG. 10A and FIG. 10B are cross-sectional views for illustrating a stepthat follows FIG. 9A and FIG. 9B.

FIG. 1A and FIG. 11B are cross-sectional views for illustrating a stepthat follows FIG. 10A and FIG. 10B.

FIG. 12A and FIG. 12B are cross-sectional views for illustrating a stepthat follows FIG. 1A and FIG. 11B.

FIG. 13A and FIG. 13B are cross-sectional views for illustrating a stepthat follows FIG. 12A and FIG. 12B.

FIG. 14A and FIG. 14B are cross-sectional views for illustrating a stepthat follows FIG. 13A and FIG. 13B.

FIG. 15 is a plan view for illustrating the configuration andarrangement of the thin-film coil of the thin-film magnetic head of thefirst embodiment of the invention.

FIG. 16 is a perspective view for illustrating the configuration of thethin-film magnetic head of the first embodiment.

FIG. 17A and FIG. 17B are cross-sectional views for illustrating a stepin a modification example of the method of manufacturing the thin-filmmagnetic head of the first embodiment.

FIG. 18A and FIG. 18B are cross-sectional views for illustrating a stepin a method of manufacturing a thin-film magnetic head of a secondembodiment of the invention.

FIG. 19A and FIG. 19B are cross-sectional views for illustrating a stepthat follows FIG. 18A and FIG. 18B.

FIG. 20A and FIG. 20B are cross-sectional views for illustrating a stepthat follows FIG. 19A and FIG. 19B.

FIG. 21 is a view for illustrating the typical method of forming thestepped portion in the bottom pole layer for defining the throat height.

FIG. 22 is a view for illustrating the typical method of forming thestepped portion in the bottom pole layer for defining the throat height.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the invention will now be described in detail withreference to the accompanying drawings.

[First Embodiment]

Reference is now made to FIG. 1A to FIG. 14A, FIG. 1B to FIG. 14B, FIG.15 and FIG. 16 to describe a method of manufacturing a thin-filmmagnetic head of a first embodiment of the invention. FIG. 1A to FIG.14A are cross sections orthogonal to the air bearing surface and the topsurface of a substrate. FIG. 1B to FIG. 14B are cross sections ofmagnetic pole portions each of which is parallel to the air bearingsurface. FIG. 15 is a plan view showing the configuration andarrangement of a thin-film coil of the thin-film magnetic head of theembodiment. FIG. 16 is a perspective view for illustrating theconfiguration of the thin-film magnetic head in which an overcoat layeris omitted.

In the method of manufacturing the thin-film magnetic head of theembodiment, a step shown in FIG. 1A and FIG. 1B is first performed. Inthe step an insulating layer 2 made of alumina (Al₂O), for example, isdeposited to a thickness of approximately 1 to 3 μm on a substrate 1made of aluminum oxide and titanium carbide (Al₂O₃—TiC), for example.Next, a bottom shield layer 3 for a read head, made of a magneticmaterial such as Permalloy and having a thickness of approximately 2 to3 μm, is formed on the insulating layer 2. The bottom shield layer 3 isselectively formed on the insulating layer 2 by plating through the useof a photoresist film as a mask, for example. Although not shown, aninsulating layer that is made of alumina, for example, and has athickness of 3 to 4 μm, for example, is formed over the entire surface.The insulating layer is then polished by chemical mechanical polishing(hereinafter referred to as CMP), for example, to expose the bottomshield layer 3 and to flatten the surface.

On the bottom shield layer 3, a bottom shield gap film 4 serving as aninsulating film and having a thickness of approximately 20 to 40 nm, forexample, is formed. On the bottom shield gap film 4, an MR element 5 formagnetic signal detection having a thickness of tens of nanometers isformed. For example, the MR element 5 may be formed by selectivelyetching an MR film formed by sputtering. The MR element 5 is locatednear a region in which the air bearing surface described later is to beformed. The MR element 5 may be an element made up of a magnetosensitivefilm that exhibits magnetoresistivity, such as an AMR element, a GMRelement or a TMR (tunnel magnetoresistive) element. Next, although notshown, a pair of electrode layers, each having a thickness of tens ofnanometers, to be electrically connected to the MR element 5 are formedon the bottom shield gap film 4. A top shield gap film 7 serving as aninsulating film and having a thickness of approximately 20 to 40 nm, forexample, is formed on the bottom shield gap film 4 and the MR element 5.The MR element 5 is embedded in the shield gap films 4 and 7. Examplesof insulating materials used for the shield gap films 4 and 7 includealumina, aluminum nitride, and diamond-like carbon (DLC). The shield gapfilms 4 and 7 may be formed by sputtering or chemical vapor deposition(hereinafter referred to as CVD).

Next, a top shield layer 8 for a read head, made of a magnetic materialand having a thickness of approximately 1.0 to 1.5 μm, is selectivelyformed on the top shield gap film 7. Next, although not shown, aninsulating layer made of alumina, for example, and having a thickness of2 to 3 μm, for example, is formed over the entire surface, and polishedby CMP, for example, so that the top shield layer 8 is exposed, and thesurface is flattened.

An insulating layer 9 made of alumina, for example, and having athickness of approximately 0.3 μm, for example, is formed over theentire top surface of the layered structure obtained through theforegoing steps. On the entire top surface of the insulating layer 9, afirst layer 10 a of the bottom pole layer 10 made of a magnetic materialand having a thickness of approximately 0.5 to 1.0 μm is formed. Thefirst layer 10 a has a top surface that is flat throughout. The bottompole layer 10 includes the first layer 10 a, and a second layer 10 b, athird layer 10 d, a fourth layer 10 f, and coupling layers 10 c, 10 eand 10 g that will be described later.

The first layer 10 a may be formed by plating, using NiFe (80 weight %Ni and 20 weight % Fe), or a high saturation flux density material suchas NiFe (45 weight % Ni and 55 weight % Fe), CoNiFe (10 weight % Co, 20weight % Ni and 70 weight % Fe), or FeCo (67 weight % Fe and 33 weight %Co). Alternatively, the first layer 10 a may be formed by sputtering,using a high saturation flux density material such as CoFeN, FeAlN, FeN,FeCo, or FeZrN. In this embodiment the first layer 10 a is formed bysputtering to have a thickness of 0.5 to 1.0 μm by way of example.

Next, an insulating film 11 made of alumina, for example, and having athickness of 0.2 μm, for example, is formed on the first layer 10 a. Theinsulating film 11 is then selectively etched to form openings in theinsulating film 11 in regions in which the second layer 10 b and thecoupling layer 10 c are to be formed.

Next, although not shown, an electrode film of a conductive materialhaving a thickness of 50 to 80 nm is formed by sputtering, for example,so as to cover the first layer 10 a and the insulating film 11. Thiselectrode film functions as an electrode and a seed layer for plating.Next, although not shown, a frame is formed on the electrode film byphotolithography. The frame will be used for forming a first coil 13 byplating.

Next, electroplating is performed, using the electrode film, to form thefirst coil 13 made of a metal such as copper (Cu) and having a thicknessof approximately 3.0 to 3.5 μm. The first coil 13 is disposed in theregion in which the insulating film 11 is located. Next, the frame isremoved, and portions of the electrode film except the portion below thefirst coil 13 are then removed by ion beam etching, for example.

Next, although not shown, a frame is formed on the first layer 10 a andthe insulating film 11 by photolithography. The frame will be used forforming the second layer 10 b and the coupling layer 10 c of the bottompole layer 10 by frame plating.

FIG. 2A and FIG. 2B illustrate the following step. In the stepelectroplating is performed to form the second layer 10 b and thecoupling layer 10 c, each of which is made of a magnetic material andhas a thickness of 3.5 to 4.0 μm, for example, on the first layer 10 a.For example, the second layer 10 b and the coupling layer 10 c may bemade of NiFe, CoNiFe or FeCo. In the present embodiment the second layer10 b and the coupling layer 10 c are made of CoNiFe having a saturationflux density of 1.9 to 2.3 tesla (T) by way of example. In theembodiment, when the second layer 10 b and the coupling layer 10 c areformed by plating, no specific electrode film is provided, but theunpatterned first layer 10 a is used as an electrode and a seed layerfor plating.

Next, although not shown, a photoresist layer is formed to cover thefirst coil 13, the second layer 10 b and the coupling layer 10 c. Usingthe photoresist layer as a mask, the first layer 10 a is selectivelyetched by reactive ion etching or ion beam etching, for example. Thefirst layer 10 a is thus patterned. Next, the photoresist layer isremoved.

FIG. 3A and FIG. 3B illustrate the following step. In the step aninsulating layer 15 made of photoresist, for example, is formed in aregion in which a second coil 19 described later is to be located. Theinsulating layer 15 is formed so that at least the space between thesecond layer 10 b and the first coil 13, the space between the turns ofthe first coil 13, and the space between the coupling layer 10 c and thefirst coil 13 are filled with the insulating layer 15. Next, aninsulating layer 16 made of alumina, for example, and having a thicknessof 4 to 6 μm is formed so as to cover the insulating layer 15.

FIG. 4A and FIG. 4B illustrate the following step. In the step theinsulating layers 15 and 16 are polished by CMP, for example, so thatthe second layer 10 b, the coupling layer 10 c and the insulating layer15 are exposed, and the top surfaces of the second layer 10 b, thecoupling layer 10 c and the insulating layers 15 and 16 (which is notshown in FIG. 4A and FIG. 4B) are flattened.

FIG. 5A and FIG. 5B illustrate the following step. In the step theinsulating layer 15 is removed, and an insulating film 17 made ofalumina, for example, is then formed by CVD, for example, so as to coverthe entire top surface of the layered structure. As a result, groovescovered with the insulating film 17 are formed in the space between thesecond layer 10 b and the first coil 13, the space between the turns ofthe first coil 13, and the space between the coupling layer 10 c and thefirst coil 13. The insulating film 17 has a thickness of 0.08 to 0.15μm, for example. The insulating film 17 may be formed by CVD, forexample, in which H₂O, N₂, N₂O, or H₂O₂ as a material used for makingthin films and Al(CH)₃ or AlCl₃ as a material used for making thin filmsare alternately ejected in an intermittent manner under a reducedpressure at a temperature of 180 to 220° C. Through this method, aplurality of thin alumina films are stacked so that the insulating film17 that is closely-packed and exhibits a good step coverage, and has adesired thickness is formed.

Next, a first conductive film made of Cu, for example, and having athickness of 50 nm, for example, is formed by sputtering so as to coverthe entire top surface of the layered structure. On the first conductivefilm, a second conductive film made of Cu, for example, and having athickness of 50 nm, for example, is formed by CVD. The second conductivefilm is not intended to be used for entirely filling the groove betweenthe second layer 10 b and the first coil 13, the groove between theturns of the first coil 13, and the groove between the coupling layer 10c and the first coil 13, but is intended to cover the grooves, takingadvantage of good step coverage of CVD. The first and second conductivefilms in combination are called an electrode film. The electrode filmfunctions as an electrode and a seed layer for plating. Next, on theelectrode film, a conductive layer 19 p made of a metal such as Cu andhaving a thickness of 3 to 4 μm, for example, is formed by plating. Theelectrode film and the conductive layer 19 p are used for making thesecond coil 19. The conductive layer 19 p of Cu is formed throughplating on the second conductive film of Cu formed by CVD, so that thesecond coil is properly formed in the space between the second layer 10b and the first coil 13, the space between the turns of the first coil13, and the space between the coupling layer 10 c and the first coil 13.

FIG. 6A and FIG. 6B illustrate the following step. In the step theconductive layer 19 p is polished by CMP, for example, so that thesecond layer 10 b, the coupling layer 10 c, and the first coil 13 areexposed. As a result, the second coil 19 is made up of the conductivelayer 19 p and the electrode film that remain in the space between thesecond layer 10 b and the first coil 13, the space between the turns ofthe first coil 13, and the space between the coupling layer 10 c and thefirst coil 13. The above-mentioned polishing is performed such that eachof the second layer 10 b, the coupling layer 10 c, the first coil 13 andthe second coil 19 has a thickness of 2.0 to 3.0 μm, for example. Thesecond coil 19 has turns at least part of which is disposed betweenturns of the first coil 13. The second coil 19 is formed such that onlythe insulating film 17 is provided between the turns of the first coil13 and the turns of the second coil 19.

FIG. 15 illustrates the first coil 13 and the second coil 19. FIG. 6A isa cross section taken along line 6A-6A of FIG. 15. Connecting layers 21,46 and 47, the top pole layer 30 and the air bearing surface 42 thatwill be formed later are shown in FIG. 15, too. As shown in FIG. 15, aconnecting portion 13 a is provided near an inner end of the first coil13. A connecting portion 13 b is provided near an outer end of the firstcoil 13. A connecting portion 19 a is provided near an inner end of thesecond coil 19. A connecting portion 19 b is provided near an outer endof the second coil 19.

In the step of forming the first coil 13 or the step of forming thesecond coil 19, two lead layers 44 and 45 are formed to be disposedoutside the first layer 10 a of the bottom pole layer 10, as shown inFIG. 15. The lead layers 44 and 45 have connecting portions 44 a and 45a, respectively.

The connecting portions 13 a and 19 b are connected to each otherthrough a connecting layer 21 that will be formed later. The connectingportions 44 a and 13 b are connected to each other through a connectinglayer 46 that will be formed later. The connecting portions 19 a and 45a are connected to each other through a connecting layer 47 that will beformed later.

FIG. 7A and FIG. 7B illustrate the following step. In the step aninsulating film 20 made of alumina, for example, and having a thicknessof 0.1 to 0.3 μm is formed to cover the entire top surface of thelayered structure. Etching is selectively performed on the insulatingfilm 20 in the portions corresponding to the second layer 10 b, thecoupling layer 10 c, the two connecting portions 13 a and 13 b of thefirst coil 13, the two connecting portions 19 a and 19 b of the secondcoil 19, the connecting portion 44 a of the lead layer 44, and theconnecting portion 45 a of the lead layer 45. The insulating film 20thus etched covers the top surfaces of the coils 13 and 19 except thetwo connecting portions 13 a and 13 b of the first coil 13 and the twoconnecting portions 19 a and 19 b of the second coil 19.

Next, the connecting layers 21, 46 and 47 of FIG. 15 are formed by frameplating, for example. The connecting layers 21, 46 and 47 are made of ametal such as Cu and each have a thickness of 0.8 to 1.5 μm, forexample.

Next, a third layer 10 d is formed on the second layer 10 b, and acoupling layer 10 e is formed on the coupling layer 10 c each by frameplating, for example. The third layer 10 d and the coupling layer 10 emay be made of NiFe, CoNiFe or FeCo, for example. In the embodiment thethird layer 10 d and the coupling layer 10 e are made of CoNiFe having asaturation flux density of 1.9 to 2.3 T by way of example. The thirdlayer 10 d and the coupling layer 10 e each have a thickness of 0.8 to1.5 μm, for example.

Next, an insulating film 22 made of alumina, for example, and having athickness of 1 to 2 μm is formed to cover the entire top surface of thelayered structure. The insulating film 22 is then polished by CMP, forexample. This polishing is performed such that the top surfaces of thethird layer 10 d, the coupling layer 10 e, the connecting layers 21, 46and 47, and the insulating film 22 are flattened and each of theselayers has a thickness of 0.3 to 1.0 μm.

Next, although not shown, a magnetic layer made of a magnetic materialand having a thickness of 0.3 to 0.5 μm is formed by sputtering, so asto cover the entire top surface of the layered structure. The magneticlayer may be made of a high saturation flux density material such asCoFeN, FeAlN, FeN, FeCo, or FeZrN. In the embodiment the magnetic layeris made of CoFeN having a saturation flux density of 2.4 T by way ofexample.

FIG. 8A and FIG. 8B illustrate the following step. In the step, on themagnetic layer, an etching mask 24 a is formed in the portioncorresponding to the third layer 10 d, and an etching mask 24 b isformed in the portion corresponding to the coupling layer 10 e. Each ofthe etching masks 24 a and 24 b has an undercut so that the bottomsurface is smaller than the top surface in order to facilitate lift-offthat will be performed later. Such etching masks 24 a and 24 b may beformed by patterning a resist layer made up of two stacked organicfilms, for example.

Next, the magnetic layer is selectively etched by ion beam etching, forexample, through the use of the etching masks 24 a and 24 b. The fourthlayer 10 f and the coupling layer 10 g are thereby formed on the thirdlayer 10 d and the coupling layer 10 e, respectively. The fourth layer10 f and the coupling layer 10 g are made up of portions of the magneticlayer remaining under the etching masks 24 a and 24 b after the etching.This etching is performed such that the direction in which ion beamsmove forms an angle in a range of 0 to 20 degrees inclusive with respectto the direction orthogonal to the top surface of the first layer 10 a.Next, to remove deposits on the sidewalls of the magnetic layer 23 afterthe etching, another etching is performed such that the direction inwhich ion beams move forms an angle in a range of 60 to 75 degreesinclusive with respect to the direction orthogonal to the top surface ofthe first layer 10 a.

Next, an insulating layer 25 made of alumina, for example, and having athickness of 0.4 to 0.6 μm is formed so as to cover the entire topsurface of the layered structure while the etching masks 24 a and 24 bare left unremoved. The insulating layer 25 is formed in a self-alignedmanner so as to fill the etched portion of the above-mentioned magneticlayer. The etching masks 24 a and 24 b are then lifted off. Next, CMP isperformed for a short period of time, for example, to polish and flattenthe top surfaces of the fourth layer 10 f, the coupling layer 10 g andthe insulating layer 25. This polishing removes small differences inlevels between the fourth layer 10 f and the insulating layer 25, andbetween the coupling layer 10 g and the insulating layer 25, and removesremainders and burrs of the etching masks 24 a and 24 b after lift-offis performed.

FIG. 9A and FIG. 9B illustrate the following step. In the step arecording gap layer 26 having a thickness of 0.07 to 0.1 μm is formed tocover the entire top surface of the layered structure. The recording gaplayer 26 may be made of an insulating material such as alumina or anonmagnetic metal material such as Ru, NiCu, Ta, W or NiB. Next, aportion of the recording gap layer 26 corresponding to the couplinglayer 10 g is selectively etched.

Next, an etching mask 28 a is formed on the recording gap layer 26, andan etching mask 28 b is formed on the coupling layer 10 g. The etchingmask 28 a is a mask used for making an end portion of the recording gaplayer 26 for defining the throat height, and disposed above the fourthlayer 10 f. Each of the etching masks 28 a and 28 b has an undercut sothat the bottom surface is smaller than the top surface in order tofacilitate lift-off that will be performed later. Such etching masks 28a and 28 b may be formed by patterning a resist layer made up of twostacked organic films, for example.

FIG. 10A and FIG. 10B illustrate the following step. In the step therecording gap layer 26 is selectively etched by ion beam etching, forexample, through the use of the etching masks 28 a and 28 b, andfurthermore, the fourth layer 10 f is selectively etched to a depthsomewhere in the middle of the thickness of the fourth layer 10 f. Thedepth to which the fourth layer 10 f is etched preferably falls within arange of 0.1 to 0.4 μm inclusive, and more preferably within a range of0.1 to 0.3 μm inclusive. An end portion 26 a of the recording gap layer26 for defining the throat height is formed by this etching.

Next, a nonmagnetic layer 31 made of a nonmagnetic material is formed bylift-off. That is, the nonmagnetic layer 31 having a thickness of 0.2 to0.8 μm is formed to cover the entire top surface of the layeredstructure while the etching masks 28 a and 28 b are left unremoved. Thenonmagnetic layer 31 is formed in a self-aligned manner such that theetched portions of the recording gap layer 26 and the fourth layer 10 fare filled with the nonmagnetic layer 31. The nonmagnetic layer 31 ispreferably formed such that the top surface thereof is located in nearlythe same level as the top surface of the recording gap layer 26. Thenonmagnetic layer 31 may be made of an insulating material such asalumina.

FIG. 11A and FIG. 11B illustrate the following step. In the step theetching masks 28 a and 28 b are lifted off, and the top surfaces of therecording gap layer 26 and the nonmagnetic layer 31 are then polishedand flattened by CMP, for example. In FIG. 11A and FIG. 11B numeral 32indicates the level in which polishing is stopped. This polishing isperformed to such a degree that the uneven portions created in therecording gap layer 26 and the nonmagnetic layer 31 are removed. Thedepth to which the polishing is performed falls within a range of 10 to50 nm inclusive, for example.

FIG. 12A and FIG. 12B illustrate the following step. In the step amagnetic layer 33 made of a magnetic material and having a thickness of0.05 to 0.5 μm is formed by sputtering, for example, on the entire topsurface of the layered structure. The magnetic layer 33 is made of ahigh saturation flux density material such as CoFeN, FeAlN, FeN, FeCo orFeZrN. The magnetic layer 33 preferably has a higher saturation fluxdensity. In the embodiment the magnetic layer 33 is made of CoFeN havinga saturation flux density of 2.4 T by way of example. The magnetic layer33 is connected to the coupling layer 10 g.

Next, a magnetic layer 30 b made of a magnetic material is formed byframe plating, for example, on the magnetic layer 33, wherein themagnetic layer 33 is used as an electrode and a seed layer. The magneticlayer 30 b has a thickness of 3 to 4 μm, for example. The magnetic layer30 b may be made of CoNiFe or FeCo having a saturation flux density of2.3 T, for example. The magnetic layer 30 b is disposed to extend from aregion corresponding to the recording gap layer 26 to a regioncorresponding to the coupling layer 10 g.

FIG. 13A and FIG. 13B illustrate the following step. In the step themagnetic layer 33 and the recording gap layer 26 are selectively etchedby ion beam etching, for example, using the magnetic layer 30 b as anetching mask. The magnetic layer 33 thus etched is a magnetic layer 30 awhose plane geometry is the same as that of the magnetic layer 30 b.After the above-mentioned etching is performed, the magnetic layer 30 bhas a thickness of 1 to 2 μm, for example. The top pole layer 30 is madeup of the magnetic layers 30 a and 30 b.

As shown in FIG. 16, the top pole layer 30 includes a track widthdefining portion 30A and a yoke portion 30B. The track width definingportion 30A has an end located in the air bearing surface 42 and theother end located away from the air bearing surface 42. The yoke portion30B is coupled to the other end of the track width defining portion 30A.The track width defining portion 30A has a uniform width. The trackwidth defining portion 30A initially has a width of about 0.15 to 0.2μm, for example. The yoke portion 30B is equal in width to the trackwidth defining portion 30A at the interface with the track widthdefining portion 30A. The yoke portion 30B gradually increases in widthas the distance from the track width defining portion 30A increases, andmaintains a specific width to the end.

Next, although not shown, a photoresist mask having an opening aroundthe track width defining portion 30A is formed. Using the photoresistmask and the track width defining portion 30A as masks, a portion of thefourth layer 10 f is etched. This etching may be performed such that thedirection in which ion beams move forms an angle in a range of 35 to 55degrees inclusive, for example, with respect to the direction orthogonalto the top surface of the first layer 10 a. The depth to which thefourth layer 10 f is etched is preferably 0.1 to 0.4 μm, and morepreferably 0.1 to 0.3 μm. If the depth to which the etching is performedis 0.5 μm or greater, the occurrences of side write or side eraseincrease. Side write is that data is written in a track adjacent to theintended track. Side erase is that data written in a track adjacent tothe intended track is erased.

A trim structure is thereby formed, wherein a portion of the fourthlayer 10 f, the recording gap layer 26, and the track width definingportion 30A have the same widths in the air bearing surface. The trimstructure suppresses an increase in the effective recording track widthdue to expansion of a magnetic flux generated during writing in a narrowtrack.

Next, sidewalls of the portion of the fourth layer 10 f, the recordinggap layer 26, and the track width defining portion 30A are etched by ionbeam etching, for example, to reduce the widths of these layers in theair bearing surface down to 0.1 μm, for example. This etching may beperformed such that the direction in which ion beams move forms an anglein a range of 40 to 75 degrees inclusive, for example, with respect tothe direction orthogonal to the top surface of the first layer 10 a.

FIG. 14A and FIG. 14B illustrate the following step. In the step theovercoat layer 34 made of alumina, for example, and having a thicknessof 20 to 30 μm is formed so as to cover the entire top surface of thelayered structure. The surface of the overcoat layer 34 is flattened,and electrode pads (not shown) are formed thereon. Finally, the sliderincluding the foregoing layers is lapped to form the air bearing surface42. The thin-film magnetic head including the read and write heads isthus completed.

According to the embodiment, the following method may be employed toform the top pole layer 30 as shown in FIG. 17A and FIG. 17B, instead offorming the top pole layer 30 by frame plating. FIG. 17A is a crosssection orthogonal to the air bearing surface and the top surface of thesubstrate. FIG. 17B is a cross section of the pole portions parallel tothe air bearing surface. In this method a magnetic layer made of amagnetic material and having a thickness of 1.0 to 1.5 μm is formed bysputtering on the entire top surface of the layered structure includingthe flattened top surfaces of the recording gap layer 26 and thenonmagnetic layer 31. The magnetic layer may be made of CoFeN or FeCohaving a saturation flux density of 2.4 T. Next, an insulating layermade of alumina, for example, and having a thickness of 0.3 to 2.0 μm isformed on the magnetic layer. Next, an etching mask having a thicknessof 0.5 to 1.0 μm, for example, is formed by frame plating, for example,on the insulating layer. The etching mask may be made of NiFe (45 weight% Ni and 55 weight % Fe), CoNiFe (67 weight % Co, 15 weight % Ni and 18weight % Fe) having a saturation flux density of 1.9 to 2.1 T, or FeCo(60 weight % Fe and 40 weight % Co) having a saturation flux density of2.3 T. The plane geometry of the etching mask is the same as that of themagnetic layer 30 b. The etching mask has a portion for defining thetrack width. This portion has a width of 0.1 to 0.2 μm, for example.

Next, the insulating layer is selectively etched by reactive ionetching, for example, using the etching mask. A halogen gas such as Cl₂or a mixture of BCl₃ and Cl₂ is utilized for this etching. The etchingmask may be either removed or left unremoved through the etching. If theetching mask is removed, it is possible to perform etching of themagnetic layer later with more accuracy. Next, the magnetic layer isselectively etched by reactive ion etching, for example, using theinsulating layer as another etching mask 39. The magnetic layer ispreferably etched at a temperature of 50° C. or higher so that theetching rate is increased. More preferably, the temperature falls withinthe range of 200 to 300° C. inclusive so that the etching is moresuccessfully performed. The magnetic layer that has been etched servesas the top pole layer 30.

To form the top pole layer 30 by etching the magnetic layer throughreactive ion etching as described above, the recording gap layer 26 ispreferably made of a nonmagnetic inorganic material such as alumina,silicon carbide (SiC), or aluminum nitride (AlN). It is thereby possiblethat the etching rate of the recording gap layer 26 is lower than thatof the magnetic layer when the magnetic layer made of a magneticmaterial including at least iron that is one of the group consisting ofiron and cobalt, such as CoFeN or FeCo, is etched by reactive ionetching. As a result, the sidewalls of the magnetic layer that has beenetched form an angle of nearly 90 degrees with respect to the topsurface of the recording gap layer 26. It is thereby possible to definethe track width with accuracy.

This feature will now be described in detail. For example, a case isconsidered wherein the magnetic layer including at least iron that isone of the group consisting of iron and cobalt is etched by reactive ionetching, using the etching mask 39 made of alumina. In this case, aproduct formed through a plasma reaction between Cl₂ of the etching gasand iron or iron and cobalt of the magnetic layer deposits on thesidewalls of the magnetic layer that has been etched. As a result,during the etching, until the bottom portion formed through the etchingreaches the neighborhood of the recording gap layer 26, the magneticlayer etched is likely to have the shape in which the width thereofincreases as the distance to the lower portion of the magnetic layerdecreases. However, the amount of the above-mentioned product formedthrough the plasma reaction extremely decreases when the bottom portionformed through the etching reaches the neighborhood of the recording gaplayer 26. If the etching is further continued after the bottom portionreaches the recording gap layer 26, portions of the sidewalls of themagnetic layer etched, the portions being near the bottom portion, arethen etched, and the magnetic layer etched finally has a shape in whichthe sidewalls of the magnetic layer etched form an angle of nearly 90degrees with respect to the top surface of the recording gap layer 26.To form the magnetic layer having such a shape, it is required that theother magnetic layer below the recording gap layer 26 would not beexposed during the etching until the magnetic layer etched has theabove-mentioned shape. This is because, if the other magnetic layerbelow the recording gap layer 26 is exposed during the etching, aproduct of a plasma reaction formed through the etching of the magneticlayer exposed deposits on the sidewalls of the magnetic layer etched.

Here, if the recording gap layer 26 is made of a nonmagnetic inorganicmaterial such as alumina, silicon carbide (SiC), or aluminum nitride(AIN), the etching rate of the recording gap layer 26 is lower than thatof the magnetic layer. It is thereby possible to prevent the othermagnetic layer below the recording gap layer 26 from being exposedduring the etching until the magnetic layer etched has theabove-mentioned shape. As a result, the sidewalls of the magnetic layerthat has been etched form an angle of nearly 90 degrees with respect tothe top surface of the recording gap layer 26.

The following are preferred conditions for etching the magnetic layer byreactive ion etching as described above. The pressure in the chamber(the degree of vacuum) is preferably 0.1 to 1.0 Pa. The temperature atwhich the etching is performed is preferably 200 to 300° C. The etchinggas preferably includes Cl₂, and more preferably includes BCl₃ and CO₂,in addition to Cl₂. The flow rate of Cl₂ of the etching gas ispreferably 100 to 300 ccm. The flow rate of BCl₃ of the etching gas ispreferably 50% of the flow rate of Cl₂ or lower. If the flow rate ofBCl₃ is higher than 50% of the flow rate of Cl₂, alumina is likely to beetched. The flow rate of CO₂ of the etching gas is preferably 10% of theflow rate of Cl₂ or lower. If the flow rate of CO₂ is higher than 10% ofthe flow rate of Cl₂, the sidewalls form a greater angle with respect tothe direction orthogonal to the top surface of the recording gap layer26. The substrate bias for the etching is preferably 150 to 500 W.

For etching the magnetic layer by reactive ion etching as describedabove, the etching mask 39 is preferably made of a nonmagnetic inorganicmaterial such as alumina, silicon carbide (SiC), or aluminum nitride(AlN), which is similar to the recording gap layer 26. This is because,as in the case of the recording gap layer 26, the etching rate of theetching mask 39 is lower than that of the magnetic layer when themagnetic layer made of a magnetic material including at least iron thatis one of the group consisting of iron and cobalt, such as CoFeN orFeCo, is etched by reactive ion etching.

If the magnetic layer is etched by reactive ion etching and the top polelayer 30 is thereby formed as described above, the recording gap layer26 is then etched by ion beam etching, for example, using the top polelayer 30 as a mask. Next, a photoresist mask (not shown) having anopening around the track width defining portion 30A is formed. A portionof the fourth layer 10 f is etched by ion beam etching, for example,using the photoresist mask and the track width defining portion 30A asmasks. A trim structure is thereby formed.

According to the embodiment, the second coil 19 may be made by thefollowing method, instead of the method described with reference to FIG.3A to FIG. 6A, and FIG. 3B to FIG. 6B. In this method the insulatingfilm 17 is formed in addition to the state shown in FIG. 2A and FIG. 2Bto cover the entire top surface of the layered structure. Next, anelectrode film is formed to cover the entire top surface of the layeredstructure. On the electrode film the conductive layer 19 p made of ametal such as Cu and having a thickness of 3 to 4 μm, for example, isformed by frame plating, for example. Next, portions of the electrodefilm except the portion below the conductive layer 19 p are removed byion beam etching, for example. Next, an insulating layer made of aluminaand having a thickness of 3 to 5 μm is formed to cover the entire topsurface of the layered structure. The insulating layer is then polishedby CMP, for example, so that the second layer 10 b, the coupling layer10 c and the first coil 13 are exposed. The second coil 19 is therebymade up of the conductive layer 19 p and the electrode film remaining inthe space between the second layer 10 b and the first coil 13, the spacebetween the turns of the first coil 13, and the space between thecoupling layer 10 c and the first coil 13.

The thin-film magnetic head according to the present embodimentcomprises the air bearing surface 42 serving as a medium facing surfacethat faces toward a recording medium. The magnetic head furthercomprises the read head and the write head (the induction-typeelectromagnetic transducer).

The read head includes: the MR element 5 located near the air bearingsurface 42; the bottom shield layer 3 and the top shield layer 8 forshielding the MR element 5; the bottom shield gap film 4 located betweenthe MR element 5 and the bottom shield layer 3; and the top shield gapfilm 7 located between the MR element 5 and the top shield layer 8. Theportions of the bottom shield layer 3 and the top shield layer 8 locatedon a side of the air bearing surface 42 are opposed to each other withthe MR element 5 in between.

The write head comprises the bottom pole layer 10 and the top pole layer30 that are magnetically coupled to each other and include the poleportions opposed to each other and located in the regions of the polelayers on the side of the air bearing surface 42. The write head furthercomprises: the recording gap layer 26 disposed between the pole portionof the bottom pole layer 10 and the pole portion of the top pole layer30; and the coils 13 and 19. The coils 13 and 19 are provided such thatat least part thereof is disposed between the bottom pole layer 10 andthe top pole layer 30 and insulated from the bottom pole layer 10 andthe top pole layer 30. The bottom pole layer 10 and the top pole layer30 of the present embodiment correspond to the first pole layer and thesecond pole layer of the invention, respectively.

The bottom pole layer 10 includes the first layer 10 a, the second layer10 b, the third layer 10 d, the fourth layer 10 f, and the couplinglayers 10 c, 10 e and 10 g. The first layer 10 a is disposed to beopposed to the coils 13 and 19. The second layer 10 b is disposed nearthe air bearing surface 42 and connected to the first layer 10 a in sucha manner that the second layer 10 b protrudes closer toward the top polelayer 30 than the first layer 10 a. The third layer 10 d is disposednear the air bearing surface 42 and connected to the second layer 10 bin such a manner that the third layer 10 d protrudes closer toward thetop pole layer 30 than the second layer 10 b. The fourth layer 10 f isdisposed near the air bearing surface 42 and connected to the thirdlayer 10 d in such a manner that the fourth layer 10 f protrudes closertoward the top pole layer 30 than the third layer 10 d. The couplinglayers 10 c, 10 e and 10 g make up the coupling portion 43 formagnetically coupling the bottom pole layer 10 to the top pole layer 30.

The top pole layer 30 incorporates the track width defining portion 30Afor defining the track width and the yoke portion 30B. The width of thetrack width defining portion 30A taken in the air bearing surface 42 isequal to the track width. The track width defining portion 30A is flat.

The fourth layer 10 f of the bottom pole layer 10 has a portion thatfaces toward the track width defining portion 30A of the top pole layer30, the recording gap layer 26 being disposed in between. This portionis the pole portion of the bottom pole layer 10. The track widthdefining portion 30A has a portion that faces toward the fourth layer 10f, the recording gap layer 26 being disposed in between. This portion isthe pole portion of the top pole layer 30.

As shown in FIG. 14A, the throat height is defined by the position inwhich the fourth layer 10 f and the end portion 26 a of the recordinggap layer 26 for defining the throat height are in contact with eachother. That is, throat height TH is the distance between the air bearingsurface 42 and the position in which the fourth layer 10 f and the endportion 26 a are in contact with each other. Zero throat height levelTH0 is the level of the position in which the fourth layer 10 f and theend portion 26 a are in contact with each other. Each of the fourthlayer 10 f and the top pole layer 30 preferably has a saturation fluxdensity of 2.4 T or higher.

As shown in FIG. 15, the thin-film coil of the embodiment includes thefirst coil 13, the second coil 19 and the connecting layer 21. The firstcoil 13 has turns part of which is disposed between the second layer 10b and the coupling layer 10 c. The second coil 19 has turns at leastpart of which is disposed between turns of the first coil 13. Theconnecting layer 21 is disposed on a side of the third layer 10 d andconnects the coil 13 to the coil 19 in series. Part of the turns of thesecond coil 19 is disposed between the second layer 10 b and thecoupling layer 10 c, too. The coils 13 and 19 are both flat whorl-shapedand disposed around the coupling portion 43. The coils 13 and 19 may beboth wound clockwise from the outer end to the inner end. The connectinglayer 21 connects the connecting portion 13 a of the coil 13 to theconnecting portion 19 b of the coil 19 at the minimum distance. Theconnecting layer 21 has a thickness smaller than the thickness of eachof the coils 13 and 19. The coils 13 and 19 and the connecting layer 21are all made of a metal, such as Cu. The thin-film coil of theembodiment has seven turns although the invention is not limited to theseven-turn coil.

The method of manufacturing the thin-film magnetic head of theembodiment comprises the steps of: forming the bottom pole layer 10;forming the thin-film coil (made up of the coils 13 and 19 and theconnecting layer 21) on the bottom pole layer 10; and forming therecording gap layer 26 on the pole portion of the bottom pole layer 10.

The method further comprises the steps of: forming the etching mask 28 aon the recording gap layer 26 for forming the end portion 26 a of therecording gap layer 26 for defining the throat height; and forming theend portion 26 a of the recording gap layer 26 by selectively etchingthe recording gap layer 26 and a portion of the fourth layer 10 f of thebottom pole layer 10 through the use of the etching mask 28 a. Themethod further comprises the steps of forming the nonmagnetic layer 31so as to fill the etched portions of the recording gap layer 26 and thefourth layer 10 f while the mask 28 a is left unremoved; removing themask 28 a after the nonmagnetic layer 31 is formed; flattening the topsurfaces of the recording gap layer 26 and the nonmagnetic layer 31 bypolishing such as CMP, after the mask 28 a is removed; and forming thetop pole layer 30 on the flattened top surfaces of the recording gaplayer 26 and the nonmagnetic layer 31.

The method further comprises the step of etching of the recording gaplayer 26 and a portion of the fourth layer 10 f of the bottom pole layer10 to align with the width of the track width defining portion 30A ofthe top pole layer 30 through the use of the track width definingportion 30A as a mask. Through this step each of the portion of thefourth layer 10 f, the recording gap layer 26 and the track widthdefining portion 30A is made to have a width taken in the air bearingsurface 42 that is equal to the track width.

According to the embodiment, the nonmagnetic layer 31 is formed bylift-off so as to fill the etched portions of the recording gap layer 26and the fourth layer 10 f. It is therefore possible to flatten the topsurfaces of the recording gap layer 26 and the nonmagnetic layer 31 by asmall amount of polishing. It is thereby possible to form the flat trackwidth defining portion 30A on the flat surface. The embodiment thusallows formation of the track width defining portion 30A that issmall-sized with accuracy. As a result, the track width is reduced andthe writing density is thereby enhanced. The nonmagnetic layer 31 may beformed such that the top surface thereof is disposed in the level almostthe same as the level of the top surface of the recording gap layer 26.It is thereby possible to form the track width defining portion 30A on anearly flat surface without flattening the top surfaces of the recordinggap layer 26 and the nonmagnetic layer 31 by polishing. In this case, itis possible to omit the step of flattening the top surfaces of therecording gap layer 26 and the nonmagnetic layer 31 by polishing.

According to the embodiment, the throat height is defined by theposition in which the fourth layer 10 f and the end portion 26 a of therecording gap layer 26 are in contact with each other. As a result,according to the embodiment, there is no variation in throat height dueto polishing of the bottom pole layer as described with reference toFIG. 22 even though the surface of the end portion 26 a forms an anglewith respect to the direction orthogonal to the top surface of the firstlayer 10 a. The embodiment therefore allows the throat height to becontrolled with accuracy.

According to the embodiment, the second layer 10 b, the third layer 10d, the fourth layer 10 f and the top pole layer 30 may be made of a highsaturation flux density material. It is thereby possible to prevent asaturation of flux halfway through the magnetic path. To achieve this,it is particularly effective that the fourth layer 10 f and the top polelayer 30 are made of a high saturation flux density material having asaturation flux density of 2.4 T or higher. It is thereby possible touse the magnetomotive force generated by the thin-film coil for writingwith efficiency. It is thus possible to achieve the write head having anexcellent overwrite property.

According to the embodiment, the first coil 13 is formed on the firstlayer 10 a having an entirely flat top surface. It is thus possible toform the first coil 13 that is thick but small in size with accuracy.According to the embodiment, the second coil 19 is formed such that atleast part thereof is disposed between the turns of the first coil 13.It is thereby possible to form the second coil 19 that is thick butsmall in size with accuracy, too. According to the embodiment, it is thethin insulating film 17 that separates the second layer 10 b from thesecond coil 19, the turns of the first coil 13 from the turns of thesecond coil 19, and the coupling layer 10 c from the second coil 19. Itis thereby possible that the space between the second layer 10 b and thesecond coil 19, the space between the turns of the first coil 13 and theturns of the second coil 19, and the space between the coupling layer 10c and the second coil 19 are made very small.

The foregoing features of the embodiment allow the coils 13 and 19 to bethick and the yoke length to be short. It is thereby possible to reducethe resistance of the thin-film coil while the yoke length is reduced,that is, the magnetic path length is reduced. As a result, according tothe embodiment of the invention, it is possible to achieve the thin-filmmagnetic head having a reduced magnetic path length and thus havingexcellent writing characteristics in a high frequency band, and havingthe thin-film coil with a low resistance.

According to the embodiment, an outer portion of the thin-film coil isdisposed adjacent to the second layer 10 b, the thin insulating film 17being located in between. That is, the thin-film coil is disposed nearthe air bearing surface 42. As a result, it is possible to utilize themagnetomotive force generated by the thin-film coil for writing withefficiency. It is thereby possible to achieve the write head having anexcellent overwrite property.

According to the embodiment, a coil for connecting the coil 13 to thecoil 19 in series may be provided in place of the connecting layer 21.It is thereby possible to increase the number of turns of the thin-filmcoil without increasing the yoke length while an increase in resistanceof the thin-film coil is prevented.

[Second Embodiment]

Reference is now made to FIG. 18A to FIG. 20A and FIG. 18B to FIG. 20Bto describe a method of manufacturing a thin-film magnetic head of asecond embodiment of the invention. FIG. 18A to FIG. 20A are crosssections orthogonal to the air bearing surface and the top surface ofthe substrate. FIG. 18B to FIG. 20B are cross sections of pole portionsparallel to the air bearing surface.

The method of the embodiment includes the steps up to the step offorming the nonmagnetic layer 31, as shown in FIG. 10A and FIG. 10B,that are the same as those of the first embodiment. In the secondembodiment, however, at least a portion of the nonmagnetic layer 31 nearthe end portion 26 a for defining the throat height is disposed toprotrude upward and reach a level higher than the top surface of therecording gap layer 26.

FIG. 18A and FIG. 18B illustrate the following step. In the step theetching masks 28 a and 28 b are lifted off, and a magnetic layer 50 madeof a magnetic material and having a thickness of 0.1 to 0.2 μm is thenformed by sputtering, for example, on the entire top surface of thelayered structure. In this embodiment the base layer below the magneticlayer 50 has uneven portions so that the top surface of the magneticlayer 50 has uneven portions, too. The magnetic layer 50 is made of ahigh saturation flux density material such as CoFeN, FeAlN, FeN, FeCo orFeZrN. The magnetic layer 50 preferably has a saturation flux density of2.4 T or higher. In the embodiment the magnetic layer 50 is made ofCoFeN having a saturation flux density of 2.4 T by way of example. Themagnetic layer 50 is connected to the coupling layer 10 g. The magneticlayer 50 corresponds to the first magnetic layer of the second polelayer of the invention.

Next, the top surface of the magnetic layer 50 is polished and flattenedby CMP, for example. In FIG. 18A and FIG. 18B numeral 51 indicates thelevel in which polishing is stopped. This polishing is performed to sucha degree that the uneven portions created in the top surface of themagnetic layer 50 are removed. The depth to which the polishing isperformed falls within a range of 10 to 50 nm inclusive, for example.

FIG. 19A and FIG. 19B illustrate the following step. In the step amagnetic layer 52 made of a magnetic material and having a thickness of0.05 to 0.5 μm is formed by sputtering, for example, on the entire topsurface of the layered structure. The magnetic layer 52 is made of ahigh saturation flux density material such as CoFeN, FeAlN, FeN, FeCo orFeZrN. The magnetic layer 52 corresponds to the second magnetic layer ofthe second pole layer of the invention.

Next, a magnetic layer 30 e made of a magnetic material is formed byframe plating, for example, on the magnetic layer 52, wherein themagnetic layer 52 is used as an electrode and a seed layer. The magneticlayer 30 e has a thickness of 1 to 2 μm, for example. The magnetic layer30 e may be made of CoNiFe or FeCo having a saturation flux density of2.3 T, for example. The magnetic layer 30 e is disposed to extend from aregion corresponding to the recording gap layer 26 to a regioncorresponding to the coupling layer 10 g.

FIG. 20A and FIG. 20B illustrate the following step. In the step themagnetic layer 52, the magnetic layer 50 and the recording gap layer 26are selectively etched by ion beam etching, for example, using themagnetic layer 30 e as an etching mask. The magnetic layers 52 and 50thus etched are magnetic layers 30 d and 30 c, respectively, each ofwhich has a plane geometry the same as that of the magnetic layer 30 e.The top pole layer 30 is made up of the magnetic layers 30 c, 30 d and30 e. The top pole layer 30 of the embodiment has a geometry the same asthat of the top pole layer 30 of the first embodiment.

Next, although not shown, a photoresist mask having an opening aroundthe track width defining portion 30A of the top pole layer 30 is formed.Using the photoresist mask and the track width defining portion 30A asmasks, a portion of the fourth layer 10 f is etched by ion beam etching,for example. This etching may be performed such that the direction inwhich ion beams move forms an angle in a range of 35 to 55 degreesinclusive, for example, with respect to the direction orthogonal to thetop surface of the first layer 10 a. The depth to which the fourth layer10 f is etched is preferably 0.1 to 0.4 μm, and more preferably 0.1 to0.3 μm. If the depth to which the etching is performed is 0.5 μm orgreater, the occurrences of side write or side erase increase. A trimstructure is thereby formed, wherein a portion of the fourth layer 10 f,the recording gap layer 26, and the track width defining portion 30Ahave the same widths in the air bearing surface.

Next, sidewalls of the portion of the fourth layer 10 f, the recordinggap layer 26, and the track width defining portion 30A are etched by ionbeam etching, for example, to reduce the widths of these layers in theair bearing surface down to 0.1 μm, for example. This etching may beperformed such that the direction in which ion beams move forms an anglein a range of 40 to 75 degrees inclusive, for example, with respect tothe direction orthogonal to the top surface of the first layer 10 a.

Next, the overcoat layer 34 made of alumina, for example, and having athickness of 20 to 30 μm is formed so as to cover the entire top surfaceof the layered structure. The surface of the overcoat layer 34 isflattened, and electrode pads (not shown) are formed thereon. Finally,the slider including the foregoing layers is lapped to form the airbearing surface 42. The thin-film magnetic head including the read andwrite heads is thus completed.

According to the embodiment, the throat height is defined by theposition in which the magnetic layer 30 c of the top pole layer 30 andthe end portion 26 a of the recording gap layer 26 for defining thethroat height are in contact with each other. That is, throat height THis the distance between the air bearing surface 42 and the position inwhich the magnetic layer 30 c and the end portion 26 a are in contactwith each other. Zero throat height level THO is the level of theposition in which the magnetic layer 30 c and the end portion 26 a arein contact with each other. According to the embodiment, there is novariation in throat height due to polishing of the bottom pole layer asdescribed with reference to FIG. 22 even though the surface of the endportion 26 a forms an angle with respect to the direction orthogonal tothe top surface of the first layer 10 a. The embodiment therefore allowsthe throat height to be controlled with accuracy.

The remainder of configuration, function and effects of the secondembodiment are similar to those of the first embodiment.

The present invention is not limited to the foregoing embodiments butmay be practiced in still other ways. For example, the thin-film coilincorporating the coils 13 and 19 and the connecting layer 21 isprovided in the embodiments. However, the thin-film coil of theinvention is not limited to this coil but may be a typical thin-filmcoil made up of a flat whorl-shaped coil having one turn or more.

The top pole layer may be the one in which the layer including the trackwidth defining portion 30A and the layer including the yoke portion 30Bare separated. In this case, the layer including the track widthdefining portion 30A is used as a mask used for etching for making thetrim structure.

The invention is also applicable to a thin-film magnetic head dedicatedto writing that has an induction-type electromagnetic transducer only,or a thin-film magnetic head that performs writing and reading with aninduction-type electromagnetic transducer.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

1. A method of manufacturing a thin-film magnetic head, the headcomprising: a medium facing surface that faces toward a recordingmedium; a first pole layer and a second pole layer that are magneticallycoupled to each other and include magnetic pole portions opposed to eachother and located in regions of the pole layers on a side of the mediumfacing surface; a gap layer provided between the pole portion of thefirst pole layer and the pole portion of the second pole layer; and athin-film coil, at least part of the coil being disposed between thefirst and second pole layers and insulated from the first and secondpole layers, wherein the second pole layer incorporates a track widthdefining portion for defining a track width, the method comprising thesteps of: forming the first pole layer; forming the thin-film coil onthe first pole layer; forming the gap layer on the pole portion of thefirst pole layer; forming a mask on the gap layer for making an endportion of the gap layer for defining a throat height; forming the endportion of the gap layer by selectively etching the gap layer and aportion of the first pole layer through the use of the mask; forming anonmagnetic layer so as to fill etched portions of the gap layer and thefirst pole layer while the mask is left unremoved; removing the maskafter the nonmagnetic layer is formed; and forming the second pole layeron the gap layer after the mask is removed.
 2. The method according toclaim 1, wherein the throat height is defined by a position in which theend portion of the gap layer and the first pole layer are in contactwith each other.
 3. The method according to claim 2, further comprisingthe step of flattening top surfaces of the gap layer and the nonmagneticlayer by polishing, the step being provided between the step of removingthe mask and the step of forming the second pole layer.
 4. The methodaccording to claim 3, wherein a depth to which the polishing isperformed in the step of flattening falls within a range ofapproximately 10 to 50 nm inclusive.
 5. The method according to claim 2,wherein the track width defining portion of the second pole layer ismade flat.
 6. The method according to claim 1, wherein: in the step offorming the nonmagnetic layer, at least a portion of the nonmagneticlayer near the end portion of the gap layer is disposed to protrudeupward and reach a level higher than the top surface of the gap layer;and the throat height is defined by a position in which the end portionof the gap layer and the second pole layer are in contact with eachother.
 7. The method according to claim 6, wherein: the second polelayer incorporates a first magnetic layer disposed on the gap layer anda second magnetic layer disposed on the first magnetic layer; and thestep of forming the second pole layer includes the steps of: forming thefirst magnetic layer on the gap layer; flattening a top surface of thefirst magnetic layer by polishing; and forming the second magnetic layeron the flattened top surface of the first magnetic layer.
 8. The methodaccording to claim 7, wherein a depth to which the polishing isperformed in the step of flattening falls within a range ofapproximately 10 to 50 nm inclusive.
 9. The method according to claim 1,further comprising the step of etching the gap layer and a portion ofthe first pole layer to align with a width of the track width definingportion of the second pole layer, so that each of the portion of thefirst pole layer, the gap layer and the track width defining portion hasa width taken in the medium facing surface that is equal to the trackwidth.
 10. The method according to claim 1, wherein: the step of formingthe second pole layer includes the steps of forming a magnetic layer onthe gap layer; and etching the magnetic layer by reactive ion etching sothat the magnetic layer etched serves as the second pole layer; and thegap layer is made of a nonmagnetic inorganic material.
 11. The methodaccording to claim 10, wherein the nonmagnetic inorganic material is oneof the group consisting of alumina, silicon carbide and aluminumnitride.